Filtering process and apparatus therefor



R. A. DEMME Feli. 3, '1925.

FILTERING PROCESS AND ABPARATUS THEREFOR Filed July 13, 1920 atlfoz wagPatented Feb. 3, 1925. I I v UNITED sr OFFIC R013 A. DEMME, on NEW YORK,N. Y.,.ASSIGNOR, BY MESNE ASSIGNMENTS, To DAR'OO coRro ATIpN, orWILMINGTON, DELAWA E, A CORPORATION OF DELAWARE.

FILTERING PROCESS AND APPARATUS THEREFOR.

Application filed July 1 3, 1920. Serial No. 396,036.

To all whom z't may concern: In the present invention I obviate these Beit known that I, Ron A. 'DEMME, a difiiculties by generating thefiltering pres- 55 citizen of Switzerland,- residing at New "sure at, orapproximately at, the filtering York, in the county of New York andState face itself. I make the source of pressure 5 of New York, haveinvented certain new an integral part of the filter itself; employanduseful Improvements in Filtering Procing it to produce a-centrifugalaction conesses and Apparatus Therefor, of which the fining the pressureto the region where such 0 following is a specification. pressure isuseful, i. e., atthefilter face. This invention relates to filteringproc- In practice, I provide a drum-like casing,

10 esses and apparatus therefor; and it comadvantageously capable ofdisassemblage prises a method of rapidly and cleanly filinto arcuateparts, and provide its inner tering liquid under pressure wherein the,periphery with-a filter cloth or other filtering .65 pressure islocalized next the filtering surmedium. Within the drum and travelingface, as by operating upon such liquid in in proximity to the-filterface, I provide a cylindrical filter having a rotating device a rotaryelement analogous to the rotor of the nature of the rotors ofcentrifugal of a centrifugal pump. This operates to pumps, producing apressure having its produce'a maximum pressure at or near the 70 maximumnext the inner face of said filter; filter face; and the effective pathof travel and it further comprises a cylindrical drum, of liquid underhigh pressure in filtration is filtering means on its inner periphery, akept down to a very small distance, instead rotary pressure-producingdevice. within of a great many feet, as is often the practice thefiltering means, and means for supplyin the use of filter presses. In sooperating liquid to the drum and means for removing, instead of thepressure increasing with ing liquids therefrom; all as more fully thedistance from the filter face,'thecon hereinafter set forth and asclaimed; verse is true; .the'maximum pressure re- For manufacturingpurposes forced filquired to force the liquor through the filtration isgenerally done in filter presses tering fabric is at, or. practicallyat, the operating under pump pressure; the pump face of such fabric. Theliquor to be filc-reating a pressure sufficiently heavy to force teredis therefore exposed to the maximum 30 the liquid to be filtered througha filter cloth filter pressure only for the briefest interval or thelike. In such anapparatus the least prior to being discharged throughthe filter pressure is at the point where pressure does 010th. Inpractice I maintain a flow of useful work, namely the filtering surface,liquid through the filtering device and past whereas the greatestpressure is in the the filtering face, discharging such liquid 35 pump;the discrepancy increasing as the as does not pass through the filterfabric.

operation goes on and the press cake builds In so doing, the period ofexposure to high up, adding its own resistance to the fricpressure ofthe liquor in filtering through tion in the pipes, etc., necessitatingmore the fabric is also very brief. The solids repressure in the pump.In most cases where m d in the filtering action go forward 40 th tit fli t b filt d i lar with the passing liquor and from it they andparticularly with thick or viscous may be removed in various ways toproduce liquids, the pressure required is quite high a qH f about heComposition of that and it also-must be maintained over relarlginallyeated; and this liquor may be tively long periods of time. With someSent back through the operation. For ex- 45 liquids, and notably glueand gelatin soluample, the passing liquor may be strained tions, thiscontinuance of high pressure is through a bag filter or the like and thedetrimental. In operating a filter press st rainedliquor returned to theinlet of the under pump pressure it may be said that apparatus forrepassage together with fresh practically only a relatively smallfraction liquor. v I

50 of the total initial pressure generated by the My invention may takevarious mechanexternal pump is effective on the actual ical embodiments.One convenient arrangefilter face and useful in forcing the liquor mentis illustrated in the accompanying through the filter cloth. drawings.In this showing" Figure 1 is a view .in central longitudinal verticalsection, certain parts being shown in elevation;

Figure 2 is a transverse vertical section along lines c0m of Figure 1;and

Figure 3 is a detail of a filtering screen.

In this showing, element 1 is a 2-part cylindrical casing mounted onstandards 2 and closed at the ends by disk elements 3 and 4. Interiorly,the periphery of the drum is provided with suitable grooves 5 leading todischarge outlets 6. Resting on this grooved and corrugated surface is afilter cloth or the like. As shown (see Figure 3), I protect the filtercloth 7 on each side by a metal filtering screen 8 of wire cloth orperforated metal. At the ends the cloth is held between the ends of thecylinder and the end disks. It is convenient to make the casing inQ-parts, A and B, flanged together (see Figure 2) .at ,9 and 10. Thefilter cloth and screen similarly may be made in two sections with theends held between flanges 9 and 10; or it may be one piece of materialwith a fold on one side and the lapped ends at the other. As will beobserved, by removing bolts 11 thewhole structure can be readilydisassembled; the top being lifted off and the filter screens taken out.As shown, within the cylinder is a rotatable shaft 12 which may behollow and serve as a feeding means for liquor to be treated, beingprovided with orifices 13 for that purpose. As shown, it is'jourusedwith a liquor carrying solids which naled at one end in stationarytubular feeding means 14, the. other end being, asv

inlet of the device. In treating hot liquors, the whole device may besteam jacketed or otherwise heated.

For the sake of simplicity of illustration, but one device is shown; butit is obvious that a plurality may be used and connected in series.

Presuming the structure shown is to be are to be removed, the liquor tobe treated passes in through 14 (or 17). The vanes 16.

being in rapid rotation, centrifugal pressure is produced next the innerperiphery of the cylinder; that is, next the filter member proper. Thepressure is-the most intense at this'point; Liquid passes through andLesa-ere emerges at 6. Usually I manage thefeed so that more liquidpasses into the cylinder in a time interval than is discharged at 6. Theresidue passes out through 18 and is strained at 19 to bring theproportion of liquids andsolids nearer that of the original liquid.Naturally the liquid passing out at 18 carries a greater proporation ofsolids than that entering at 14. With the connections as shown, theliquid strained into 20 will be drawn back by the suction of the devicethrough 21 for repassage together with fresh liquor going through 14.All the solids in the liquid treated in the end accumulate at 19 a,except the small amount on the inner face of the filter mem her. Thefilter member therefore may be used for an indefinitely long period.

What I claim is I 1. In filtration, the process which comprises feedingliquids into a stationary annular filter and producing pressure of saidliquid against the filter face by rapid rotation of a vane in the liquidin proximity thereto. y

2. In filtration, the process which comprises feeding liquids into astationary an.- nular filter, producing pressure of said liquid againstthe filter face by rapid rotation of a vane in proximity thereto, thefeed of liquid being greater than the speed of discharge through thefilter, removing the excess of liquid together with solids carriedthereby, straining out solids from the excess and repassing the strainedliquid into the filter together with fresh liquid.

3. In a filter, a stationary casing, annular filtering means therein,means for collecting and removing; liquid passing through the annulus, arevoluble, hollow perforated shaft within the annulus, meansforsupplying liquid to be filtered thereto and vanes mounted on theshaft, the ends of said vanes terminating near the inner surface of theannulus.

4. In afilter a stationary casingyannular filtering means on the innerwall thereof, means for feeding liquid within the annulus, a shaftcarrying vanes Within the annulus, means for removing filtered liquid,means for removing unfiltered liquid carrying solids in suspension,means for straining the unfiltered liquid and means for returning thestrained liquid for repassage.

5. In a filter, a stationary drum comprising two arcuate sectionsflanged together, a filtering mediumdisposed on the inner wall of thedrum and held by the flanged connections, end plates for the drum, ahollow revoluble shaft journaled through the end plates, vanes carriedby the shaft and terminating near the filtering medium, means forsupplying liquid to the shaft and means for removing filtered liquid.

6. In a filter, a stationary drum comprising two areuate sectionsflanged together,

ing two areuate sections'flanged together, a.

filtering medium disposed on the inner wall of the drum and held by theflanged connections, end plates for the drum, a hollow revoluble shaftcarrying vanes joufinaled through the end plates, said shaft havingliquid delivering orifices, means for supplying liquid to be filtered tosaid shaft, means for removing filtered liquid, means for removingliquid carrying solids in suspension from the drum, straining means forremoving solids from such removed liquid and a connection for deliveringstrained liquid back to said hollow shaft for repassage together withfresh liquid.

In testimony whereof, I affix my signature hereto.

. ROD A. DEMME. Witnesses:

Jnssm SEIDENBERG, Gno. L. Hoxm.

